Sympathetic nervous system and pain: Phenomenological diversity

This commentary on BLUMBERG et al. addresses complications associated with diagnostic testing for sympathetic dependence of pain that can lead to inappropriate positive and negative conclusions. In addition, it is suggested that their "ischemic" test be conceived as a test of the effect of local vascular pressure and that the two types of sensory disorders presented may differ primarily in the degree of sensitization of central pain pathways. Detailed reports with functionally-oriented testing like that done by BLUMBERG are essential for an understanding the pathophysiological mechanisms.